WASHINGTON — The Rev. Gordon Cosby spent much of his 95 years bucking mainstream Christianity, first by welcoming women, people of color and the poor as leaders and then by creating a hugely influential church with no actual physical church, no denomination and very few people.

But as a constellation of major faith leaders prepare for a service on Saturday in memory of Cosby, who died March 20, many remembered the rebellious pastor for his lasting influence on the mainstream Christian culture even as he rejected it.

Most Americans haven’t heard of Cosby or the movement he launched — the Church of the Saviour.

But some of America’s most prominent social justice pastors consider him a giant and a trailblazer for his concept of ministering to the poor and disenfranchised.

While much of American religion — particularly evangelicals, which Cosby was — spent the latter 20th century focused on building more and larger churches, Cosby focused on creating a network of tiny communities that cared only about concrete social change. A high level of commitment was required.

By the time he died, followers of the Church of the Saviour had created dozens of nonprofit organizations, including many well-known groups that serve the poor in Northwest Washington.

They include Jubilee Housing, which provides affordable housing; Potter’s House bookstore in the Adams Morgan neighborhood; Christ House, a medical facility for the homeless; For the Love of Children tutoring; Sitar Arts Center; and many others.

Cosby was considered a mentor to key figures, including Sojourners founder Jim Wallis, one of the country’s best-known evangelical progressives; writer and former Bill Clinton adviser the Rev. Tony Campolo; affordable-housing icon Jim Rouse; and Dean Snyder of Foundry United Methodist Church in Washington, where Saturday’s memorial service will be held.

“Others have said that Gordon and the Church of the Savior have had a greater impact on the Protestant church in America over the past 50 years than any other institution or movement,” Snyder wrote in a piece for The Washington Post.

“Sometimes the Church of the Savior under Gordon’s leadership seemed to me the Protestant equivalent of a Catholic religious order.”

Regular members of the Church of the Saviour community never numbered more than a few hundred, but Cosby’s ideas started to be widely shared in the 1960s, particularly among Protestants concerned about racial and economic disparity. His ideas were radical, including never having a real church building, requiring followers to commit to spiritual and social justice by working together and eschewing power to the point that he never referred to himself as the pastor he was.

If a mission or project got too big, he encouraged those involved to break apart into smaller entities in order to keep the environment nurturing and accountable.

Cosby worked until his death on his own projects, including trying to raise hundreds of thousands of dollars to establish a credit union and financial education center for the poor. He had lived in recent years with his wife of more than 70 years, Mary Campbell Cosby, at Christ House on Columbia Road in Washington.

“The distinction is between what we believe and how we actually live. Gordon made people uncomfortable who didn’t know whether or not they believed” the Bible’s call to resolve poverty and injustice, said the Rev. Becca Stelle, an ordained Lutheran pastor who left her denomination to join the Church of the Saviour movement. Stelle went on to found a small community focused on interracial harmony and supporting people coming out of jail.

“The day he met me, it was like the clouds parted,” she said. “I was working with my own cynicism about whether there were people really living it, and here he was. That in itself was a game changer.”

Some experts believe Cosby’s heyday was decades ago, and it’s hard to place an exact measure on his influence, but his ideas are now considered mainstream. Many evangelical churches in particular abandoned denominationalism — as have many Americans — and turned to focus in the last decade on poverty. Some of the best-selling Christian writers, including Shane Claiborne and Francis Chan, are pastors whose ministry is about work in the streets, living very simply, instead of church-planting.

“Words like ‘missional church’ are now a hot word, but Gordon was the missional church before it was cool,” said David Key Sr., director of Baptist studies at Emory University’s Candler School of Theology. “Seminaries have loved Gordon’s model,” he said, which calls for “church” to describe committed spiritual communities, not buildings.

“In an age when megachurches became so popular, he showed a very different model, and isn’t Gordon’s model more sustainable?” Key said.

One of Cosby’s biggest critics was Cosby himself. In 2009, he led the loosely-knit movement to get rid of its last remaining formality: a building near Dupont Circle in Washington where he gave regular sermons. He was critical of the fact that the movement had largely drawn middle- and upper-class white people; he concluded that change might be more effective if led from the bottom. At the time the building was sold, he started a few small groups that grew into Stelle’s ministry.

“We thought change should come from the top, but it turns out the bottom might be the top,” Cosby told The Post then. The groups, he said, are “closer to what I think God loves than any I’ve ever been to.”

Born in Lynchburg, Va., on July 3, 1917, to Peter Guerrant Cosby Jr. and Kathleen Gordon Cosby, he was raised a Southern Baptist. He went into seminary and became an Army chaplain in Europe in World War II.

The experience changed his view of poverty, ministry and race. When he returned, he founded Church of the Saviour, which became known in the 1960s and 1970s for staying in Adams Morgan as race riots raged.

He is survived by his wife; a brother, P.G. Cosby of Lynchburg, Va.; a sister, Ida Gordon Poole of Sarasota, Fla.; and a foster son, Michael Murphy of Washington.